Photovoltaic module

ABSTRACT

The present invention is notably directed to a photovoltaic module, or PV module, comprising an array of photovoltaic cells, or PV cells, and electrical interconnects. The array of PV cells comprises N portions, N≥2, where the portions comprise, each, disjoint sets of PV cells of the array. The electrical interconnects connect the PV cells and the N portions of the array so as for PV cells within each of said portions to be electrically connected in parallel and the N portions to be connected in series. The PV cells and the portions are connected, via said interconnects, so to output an electrical current, in operation. The electrical interconnects are otherwise configured to provide electrical signals from each of the N portions. The invention is further directed to related systems and methods of fabrication and operation.

DOMESTIC PRIORITY

This application is a continuation of U.S. application Ser. No.15/443,455, filed Feb. 27, 2017, the contents of which are incorporatedby reference herein in its entirety.

BACKGROUND

The invention relates in general to the field of photovoltaic modules,comprising arrays of photovoltaic cells arranged side-by-side,photovoltaic systems comprising such modules and related methods offabrication and operation (e.g., to optimize electrical outputs of suchmodules). In particular, the invention is related to a photovoltaicmodule comprising an array of photovoltaic cells, where the array ispartitioned into portions (e.g., quadrants) of photovoltaic cells, whichare connected in parallel in each portion, whereas the portions areconnected in series.

The following definitions are assumed throughout this description.

Photovoltaics (PV) describes the generation of electrical power byconverting solar radiation into direct current electricity throughsemiconductors exhibiting the photovoltaic effect;

A photovoltaic cell (or PV cell, also “solar cell” or “photoelectriccell”) is a solid state device that converts energy of light directlyinto electricity by virtue of the photovoltaic effect;

A photovoltaic array or module (also “solar module”, “solar panel” or“photovoltaic panel”) is an assembly of connected photovoltaic cells,where photovoltaic cells are arranged side-by-side in the array;

A photovoltaic system typically includes at least one module ofphotovoltaic cells and interconnection wiring;

Concentrated photovoltaic (CPV) systems, including high concentratorphotovoltaics (HCPV) systems, use optics (e.g., lenses) to concentrate alarge amount of sunlight onto a small area of photovoltaic materials togenerate electricity. Concentration allows for usage of smaller areas ofsolar cells.

CPV systems aim at achieving high geometrical concentrations of solarirradiance on PV cells, typically in the order of 500-3000 suns. Suchconcentrations are typically enabled by faceted mirrors, focusing lighton one single focal plane. However, the mirror topology is neverperfect. The varying focal points and acceptance apertures of theindividual mirrors lead to a non-homogenous illumination pattern on thefocal plane. Optical mixers are used in some cases, to homogenize theillumination pattern. Yet, this may come at a price of reducing theconcentration efficiency.

The concentrating optics used in CPV systems generally result innon-uniform illumination on the PV cell surface. A more uniformillumination would come at a cost of lower efficiency, since moreoptical elements need be integrated. To reduce cost of packaging andcooling, arrays of PV cells (placed side-by-side) are sometimes designedwith a common support structure which provides electricalinterconnection and cooling. However, in this configuration the PV cellsin the array are exposed to different illumination and therefore exhibitdifferent electrical output characteristics. In order to have the sameelectrical output for each PV cell, several CPV solutions rely onpairing a single optical element with a single PV cell (point-focussystems). This only works, however, when none of the optical elements isshaded by objects in the light path, e.g., neighboring systems.

Compared to point-focus systems, dense array systems use closely packedPV cells, which involve several cells per concentrating element. Suchsolutions may thus offer a cost advantage and are less prone to shading.In dense array systems, heat generation may be higher than forpoint-focus systems because there is less surface area per cell for heatdissipation. With appropriate thermal management, the heat generated ina dense array system can be used for polygeneration (i.e., production ofelectricity, heat and additional resources like, e.g., potable water orair-conditioning), which results in improved cost-performance of theoverall system.

In solar concentrators in concentrated photovoltaics, in particular inpoint focus systems, it is essential that the concentrated beam be wellaligned to the PV receiver. On this basis, the present inventors set agoal of devising a solution, which would allow a same PV receiver to beused to align a concentrated beam during assembly of the system as wellas later during tracking operation to ensure optimal illumination of thePV receiver and therefore maximizing the electrical output of thesystem.

SUMMARY

According to a first aspect, the present invention is embodied as aphotovoltaic module, or PV module, comprising an array of photovoltaiccells, or PV cells, and electrical interconnects. The array of PV cellscomprises N portions, N≥2, where the portions comprise, each, disjointsets of PV cells of the array. The electrical interconnects connect thePV cells and the N portions of the array so as for PV cells within eachof said portions to be electrically connected in parallel and the Nportions to be connected in series. The PV cells and the portions areconnected, via said interconnects, so to output an electrical current,in operation. The electrical interconnects are otherwise configured toprovide electrical signals from each of the N portions.

As electrical signals can be obtained from each of the portions, thanksto the interconnects, a feedback signal can in turn be obtained toadjust the illumination pattern on the array and, in turn, improve thein-series electrical signals as obtained in output of the portions. As aconsequence, the present solution allows electrical current of a(typically dense) photovoltaic array exposed to inhomogeneousillumination (e.g., as generated in most point-focus systems) to beextracted in such a way that each portion is exposed to a same amount ofirradiance, which increases the module's electrical efficiency as wellas the optical efficiency of the system. Additional advantages of thepresent solutions are described in the next section.

In embodiments, the electrical interconnects are further configured soas to allow a voltage (e.g., an effective voltage or an open circuitvoltage) and/or a current produced by each of the N portions to bemeasured. Yet, although voltage and/or current produced by each portionmay, in principle, be used as a feedback signal, it is most practical torely on voltages, as mere exposure to ambient light can then beexploited to align or calibrate the module. If the systems runs withoutload, the voltage measured is an open circuit voltage. However, thesystem can also be used to drive a current into a DC step-up converter,in which case an effective voltage over each of the N portions isobtained, rather than an open circuit voltage. In all cases, a voltagemay be relied upon, both in open-circuit conditions and in operatingconditions. Note that the simultaneous measurement of an open-circuitvoltage and a current would, by definition, not be possible. However,the electrical interconnects may be designed so as to allow bothquantities (i.e., a voltage and a current) to be measured at differenttimes. For example, the current flow may be interrupted, in order tomeasure an open-circuit voltage, which can be achieved by a switch orcircuit breaker suitably located in the circuit.

In some embodiments, N is even and the N portions adjoin at a center ofthe array of PV cells. In general, the array may have a polygonal shapeand the portions may be inscribed polygons. More practical, however, isto have a rectangular array with rectangularly shaped portions, to easethe design and fabrication of the electrodes, as discussed below. Forexample, the array can be rectangular and decompose into N=4 rectangularportions of distinct sets of cells, in which case each of the portionsmeet two contiguous portions at edges extending parallel to symmetryaxes of the array.

The electrical interconnects can comprise, for each of the N portions, apair of stacked electrode elements, including a top electrode elementand a bottom electrode element, each comprising elongated contactelements. The top electrode element is arranged between PV cells of saideach of the N portions and the bottom electrode element. The elongatedcontact elements of the top electrode elements are rotated by π/2 withrespect to elongated contact elements of the bottom electrode elements,so as to form crosspoint structures that electrically connect PV cellswithin said each of the N portions in parallel. Note that such aconnection scheme does not impact the areal density of PV cells in thearray or the footprint of the module.

In embodiments, the bottom electrode element of a nth portion of said Nportions is in electrical communication with the top electrode elementof a n+1th portion of said N portions, n ∈ [1, N−1], where the nthportion and the n+1th portion are contiguous in the array, whereby the Nportions are electrically connected in series. The connection schemethat results does again not impact the areal density of PV cells in thearray.

The electrical interconnects can further comprises N−1 peripheralconductors, each connecting the bottom electrode element of the nthportion with the top electrode element of the n+1th portion. Usinglateral connectors to connect portions frees some space for in-portioninterconnects and will have only a small impact on the footprint of themodule.

In some embodiments, the top electrode elements further comprise, each,a lug protruding in-plane, outwardly from the array, in electricalcontact with one of the N peripheral conductors.

According to another aspect, the invention is embodied as a photovoltaicsystem, comprising a photovoltaic module according to any of the aboveembodiments.

In embodiments, the photovoltaic system further comprises a monitoringunit, in electrical communication with the electrical interconnects ofthe module, and configured to monitor electrical signals provided fromeach of the N portions, via the electrical interconnects.

The photovoltaic system can further comprises: optical transmissionmeans configured to: direct light onto said array of PV cells; andpositioning means, so as for a position and/or an orientation of theoptical transmission means and/or the PV module to be adjustable in thePV system, via said positioning means; and a controller operativelyconnected to the positioning means to adjust said position and/or saidorientation, based on feedback signals, where the monitoring unit isoperatively connected to the controller to provide it with said feedbacksignals, based on electrical signals from said each of the N portionsthat it monitors, in operation.

In some embodiments, the monitoring unit is configured to compute saidfeedback signals by minimizing one or more differences between voltagesoutputted by the N portions, based on the monitored electrical signals.

The optical transmission means can comprises an optical concentrator,the latter configured to concentrate light onto said array of PV cells.

In embodiments, the system is a high concentrator photovoltaics system,or HCPV system.

According to another aspect, the invention is embodied as a method ofoperating a photovoltaic module according to any of the embodimentsabove. The method comprises: directing light onto said array ofphotovoltaic cells, or PV cells; collecting an output electrical currentfrom the N portions connected in series; and collecting electricalsignals from each of the N portions.

In some embodiments, the method further comprises adjusting anillumination pattern of light directed onto said array of PV cells toincrease electrical power outputted from the N portions, based onelectrical signals collected from each of the N portions.

The described methods can be implemented to operate a photovoltaicsystem comprising optical transmission means, positioning means, and acontroller, as described above, and the step of adjusting theillumination pattern is performed by adjusting a position and/or anorientation of the optical transmission means and/or the array of PVcells.

In embodiments, the method further comprises, while collectingelectrical signals from each of the N portions, measuring, via saidelectrical interconnects, a voltage from said each of the N portions,and adjusting the illumination pattern is performed based on voltagesmeasured for the N portions.

Adjusting the illumination pattern can be performed so as to minimizeone or more differences between measured voltages.

In some embodiments, said optical transmission means comprises anoptical concentrator and the step of directing light onto said array ofphotovoltaic cells comprises concentrating light onto said array of PVcells, thanks to said optical concentrator.

The illumination pattern can be repeatedly adjusted so as to track amoving source of the light.

In embodiments, the method is implemented for aligning a photovoltaicsystem as described earlier, and the optical transmission meanscomprises an optical concentrator. The method further comprises, whilecollecting electrical signals from each of the N portions: aligning thearray of PV cells and/or the optical concentrator towards a source ofthe light, to increase electrical power outputted from the N portions.

According to a final aspect, the invention is embodied as a method offabrication of a photovoltaic module according to any one of the aboveembodiments, which comprises fabricating said array of PV cells and saidelectrical interconnects.

In some embodiments, the fabrication of the array of PV cells comprises,for each of the portions, sorting cells within said each of the portionsto minimize differences between photovoltaic voltages of the sortedcells, e.g., while being exposed to different levels of illumination.

Exposing cells in a parallel, connected array to different levels ofillumination will typically not provide an optimal electrical efficiency(maximal current and maximal voltage). To improve this situation, cellscan be sorted such that cells under high illumination provide a samevoltage as cells under lower illumination. Note that there can besubstantial voltage difference between highly illuminated cells andpoorly illuminated cells. However, the sorting strategy serves tominimize the differences and therefore maximize the overall electricalefficiency. This sorting can be done differently for the differentarrays such that the electrical efficiency is optimal and all cells in afabrication batch can be used (maximal fabrication yield). This, inturn, makes it possible to reduce the production cost of the receiverand optimize the electrical yield of the receiver under the finalillumination.

Devices, systems and methods embodying the present invention will now bedescribed, by way of non-limiting examples, and in reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1, 2 and 3 are top views of a photovoltaic module, or PV module,according to embodiments. FIG. 1 depicts an illumination pattern ontothe PV module; FIG. 2 translates irradiance intensity of theillumination patter into (rounded) numbers; and FIG. 3 illustratesprinciples of electrical connections of cells within portions of themodule and of the portions, as relied on in embodiments;

FIG. 4 is a top view of a PV module as in FIGS. 1-3, illustrating howthe PV cells and portions of the modules can be connected thanks to aparticular design of interconnects, as involved in embodiments;

FIGS. 5-7 are 3D views illustrating high-level fabrication steps of a PVmodule, according to embodiments;

FIG. 8 depicts a high concentrator photovoltaics system, involving a PVmodule, according to embodiments;

FIG. 9 is a flowchart illustrating high-level steps of a fabricationmethod of a PV module, as in embodiments; and

FIG. 10 is a flowchart illustrating high-level steps of a method foradjusting an illumination pattern of light onto portions of a PV module,according to embodiments.

The accompanying drawings show simplified representations of devices orparts thereof, as involved in embodiments. Technical features depictedin the drawings are not necessarily to scale. Similar or functionallysimilar elements in the figures have been allocated the same numeralreferences, unless otherwise indicated.

DETAILED DESCRIPTION

In reference to FIGS. 1-4, an aspect of the invention is firstdescribed, which concerns a photovoltaic (PV) module 2. This modulebasically comprises an array 5 of PV cells 10 and specific electricalinterconnects 31-37. As usual, PV cells are arranged side-by-side in thearray 5.

The array 5 of PV cells 10 decomposes into N portions 20 of cells, whereN≥2 (e.g., N=4), whereby each of the portions 20 comprises disjoint setsof PV cells 10 of the array 5. That is, the portions 20 comprisesdistinct sets of cells 10. The union of all portions 20 form a supersetof cells that typically corresponds to the whole set of cells of theentire array 5. Yet, one or more cells of the PV receiver may be subjectto a partly or fully separate electrical connection scheme, e.g., forcontrol purposes. However, the N portions of the array 5 are allconnected in series.

We note that “array” as used above does not necessarily imply a squareor a rectangular structure. Rather, an “array” means an orderedarrangement of cells, e.g., aligned along rows and columns, which may bearranged according to any polygonal shape. Yet, the array 5 can berectangular in practice (i.e., it forms a matrix of n×m cells), possiblysquare (n=m). In addition, each of the N portions can comprise a samenumber nc of cells, where, e.g., nc=(n×m)/N, assuming a rectangulararray of n×m cells. For instance, the accompanying drawings depictembodiments where PV cell arrays comprise four portions, also referredto as quadrants herein.

The electrical interconnects 31-37 are configured to connect the PVcells 10 and the N portions 20 of the array 5, so as for PV cells 10within each of the portions 20 to be electrically connected in parallel,as illustrated in FIG. 3. Meanwhile, the N portions 20 are connected inseries, thanks to such interconnects 31-37, to output an electricalcurrent, in operation. Now, the present electrical interconnects 31-37are not just designed so as to extract electrical outputs from the arrayof PV cells, they are furthermore configured to provide electricalsignals from each of the N portions 20, i.e., independently. Theinterconnection elements can have a low electrical resistance (e.g.,made of copper), and further can use contacts with low electricalresistance to the PV cells.

The present module 2 will typically be part of a PV system 1 that mayfor instance comprise an optical concentrator, as assumed in FIG. 8.

The electrical interconnects 31-37, which connect PV cells in parallelin each of the portions, which are themselves connected in series, allowto mitigate “hot spots” or inequalities in the electrical current paths.In detail, since electrical signals can be obtained from each of theportions 20, a feedback signal can accordingly be obtained, which can beused to adjust the illumination pattern and, in turn, improve thein-series electrical signals as obtained in output of the PV cellportions 20. In that respect, it should be noted that the serialconnection of the N portions makes the overall voltage additive, whilethe current output is determined by the portion having the lowestcurrent output.

As a consequence, the present solution allows electrical current of a(typically dense) PV array 5 exposed to inhomogeneous illumination(e.g., as generated in most point-focus systems) to be extracted in sucha way that each cell portion is exposed to exactly (or essentially) thesame amount of irradiance. This, as it can be realized, results inincreasing the module's electrical efficiency as well as the opticalefficiency of the module 2 (or the system 1 comprising such a module).

The electrical interconnects 31-37 may for instance be adapted todeliver a voltage or current signal, or combination thereof, for eachportion, which is characteristic for the symmetry of the illuminationpattern and thereby provides a means to accurately align an illuminationpattern on a PV receiver. The same principle may be leveraged for suntracking purposes or, even, during the fabrication of the PV cells 10,as described later. Also, the present solution allows step-up converterswith a higher efficiency and use of lower amplification circuits thatare much cheaper.

On the contrary, classical serial connections of PV cells as used in theprior art suffer from imbalanced currents that require reverse biaseddiodes to prevent negative voltages on some of the cells. Now, andnotwithstanding the use of reverse biased diodes, the overall efficiencyof prior systems is suboptimal in practice. Thus, another benefit of thepresent approach is to eliminate the need for bypass diodes, which wouldelse typically be needed when different photovoltaic cells, arranged inseries, provide different photovoltaic currents.

As it turns out, the present approach allows existing methods ofsun-tracking or alignment to be improved. In addition, this approach canbe used to handle high-currents in dense array of PV cells forconcentrator PVs. It further enables methods to assemble and wire adense array of PV cells that allow high yield during fabrication ofdense PV cell arrays and high electrical efficiency of the entire arrayto be achieved.

The PV cells can be as identical as possible, in terms of electricalcharacteristics, so as for the portions to output currents that are (aspossible) identical under a perfectly symmetric illumination pattern.Now, in practice, PV cells may slightly differ in their electricalcharacteristics, within each portion, for example due to processvariation in the manufacturing of the cells. Yet, PV cells may besorted, prior to the assembly process, e.g., according to the electricalcharacteristics of these cells which are measured after cell fabricationas part of typical quality control routines. That is, cells within eachportion may be sorted such that relative photovoltaic voltages of thecells are as identical as possible under operating conditions, so thatmaximum power can be extracted, as further discussed later in respect ofanother aspect of the invention.

In general, the present electrical interconnects 31-37 may be configuredso as to enable the measure of a voltage and/or a current produced byeach of the N portions 20, based on the electrical signals they providefrom each of the N portions 20. Now, although current signals may berelied on, in principle, most practical is to rely on voltages, as mereexposure to ambient light may then be exploited to assemble or align thePV module.

In general, the array may have a polygonal shape and the portions may beinscribed polygons. Yet, the number N of portions can be even, which, inpractice, makes it easier to symmetrize an illumination pattern acrossthe array 5, be it for sun tracking or alignment purposes. In all cases,the array 5 of PV cells 10 may typically be designed so as for the Nportions 20 to adjoin at a center of the array 5. Assuming an evennumber of portions 20, the latter may further adjoin at one or morein-plane symmetry axes of the array 5 (assuming identical types of PVcells are used in each portion). For example, if N=2 portions 20 areused, they would typically meet at a vertical or horizontal symmetryaxis. However, and as noted earlier, the array 5 can involve N=4portions (quadrants), in which case the portions will typically meet(two-by-two) at a vertical or a horizontal symmetry axis. Using fourquadrants eases the design and fabrication of the elementsinterconnecting the PV cells.

In embodiments as depicted in FIGS. 1-4, the array 5 is rectangular anddecomposes into N=4 rectangular portions 20 of distinct sets of cells10. Each of the portions 20 meets two contiguous portions at boundariesextending parallel to symmetry axes of the array 5. Each portioncomprises a same number of PV cells 10, all interconnected throughelements 31-37. Also, and as said earlier, the cells can all be of asame type. Yet, the cells may slightly differ, in terms of electricalcharacteristics, and be sorted so as to even out voltages and allow amore efficient collection of electrical power, as evoked earlier.

An advantageous design of electrical interconnects will now be discussedin detail, in reference to FIGS. 4-7. Here the electrical interconnects31-37 comprise, for each of the N portions 20, a pair of stackedelectrode elements 31, 37. The pair of elements includes a top electrodeelement 31 and a bottom electrode element 37. As better seen in FIGS.5-7, the top element 31 and the bottom element 37 comprise, each,respective elongated contact elements 311, 371 (“elongated” means havingan aspect ratio>1).

As further illustrated in the fabrication sequence of FIGS. 5-7, a topelectrode element 31 is arranged between PV cells 10 and the bottomelectrode element 37 of a respective portion 20. The elongated contactelements 311 of the top electrode elements are rotated by π/2(90°) withrespect to elongated contact elements 371 of the bottom electrodeelements 37. As it can be realized, using rotated electrode elements311, 371 as shown in FIGS. 5-7 results in forming crosspoint structures311, 371 that electrically connect PV cells 10 of each portion 20 inparallel, using only two layers of elements 311, 371. This eases thefabrication of electrodes and the interconnection of the cells 10. Sucha design has no adverse impact on the areal density of PV cells andgives rise to a vertically compact electrode arrangement, which makesthe module compatible with a variety of cooling solutions.

In practice, an assembly 10, 31 of PV cells and top electrode elementcan be fabricated as follows. For each portion, the PV cells 10 arefirst placed onto a template structure, e.g., an injection molded traywith a graphite coating, comprising a template (formed by embeddedstructures) identifying positions of cells within that portion. Then, PVcells are picked and placed onto the template structure, so as to bealigned with the embedded structures. Next, a top electrode element 31is placed on top of the cells 10. Holes 317, 318 (FIG. 5) formed inopposite reinforcement strips 314, 316 of the element 31 are used tosuitably align the top element 31 on the template structure, thanks toprotruding alignment pins on the template structure. This way, thinconductors 311 get aligned between columns of cells 10. Finally, theelement 31 is soldered onto the aligned cells 10 and the resultingassembly 10, 31 is dissociated from the template structure. We note thatthe reinforcement strips 314, 316, or lugs, are not only useful duringfor the fabrication but also for the subsequent packaging process ofFIGS. 6-7.

The portions need then be connected in series, two-by-two. For example,and as depicted in FIG. 4, the bottom electrode element 37 of portion201 is electrically connected to the top electrode element 31 of portion202, whose bottom element 37 is connected to the top element 31 ofportion 203, and so on. More generally, in an array comprising Nportions, the bottom electrode element of the nth portion can beelectrically connected to the top electrode element of the n+1th(contiguous) portion, n ∈ [1, N−1].

This can be achieved thanks to a rotational arrangement of peripheral,electrical connectors 33, 35, 37 a. That is, the electricalinterconnects may comprise N−1 sets of peripheral conductors 33, 35, 37a, arranged so as to connect the bottom electrode element 37 of the nthportion with the top electrode element 31 of the n+1th portion.

The conductors 35 may for instance be mere bars, extending along oneside of the array 5, and parallel to edges of two contiguous portions 20i, 20 i+1, to which top elements 31 are soldered. Electrical contactwith the bottom electrode elements 37 may be achieved via spring contactelements 33 and additional peripheral parts 37 a. In addition, the topelectrode elements 31 can comprise, each, a lug 314 protruding in-plane,outwardly from the array 5, so as to make electrical contact with one ofthe N peripheral bars 35. As mentioned earlier, this lug 317 may alsoserve as reinforcement for the fabrication process and may compriseholes 317 for alignment purposes.

For completeness, wires or copper bars 34 a, 36 a are used to connect apower user (not shown) to the two terminals 201, 204 (so far notconnected) of the open loop formed by in-series connected portions201-202-203-204. If necessary, copper bars 34, 36 are provided to makecontact with the terminals. Connectors 31, 33, 34, 34 a, 35, 36, 36 a,37, 37 a can be made of materials (e.g., copper) designed to have a lowelectrical resistance. Also, the electrical interconnects shouldgenerally be configured to provide contacts with low electricalresistance to the PV cells 10. The PV cells and connecting elements areassembled on a substrate 40, which may possibly comprises coolingconduits or channels (not shown).

Next, according to another aspect, the invention can be embodied as amethod of fabrication of a photovoltaic module 2 as described above.Aspects of such a method have already been evoked in respect of FIGS.5-8. Basically, such a method aims at fabricating an array 5 of PVcells, partitioned into PV cell portions, as described earlier inreference to FIGS. 1-4. As described above in reference to FIGS. 5-7,suitable electrical interconnects 31-37 can be fabricated and assembled,so as to connect PV cells of each portion in parallel and the portionsin series.

As illustrated in the flowchart of FIG. 9, top electrode elements 31need be fabricated for each portion, step S1. PV cells 10 are connectedto this element 31, step S3, to form an assembly as otherwise depictedin FIG. 5. These operations are repeated for each portion, steps S4, S5.Eventually, all portions are assembled with and connected to the lowerelectrode elements 37, step S6, as previously described in reference toFIGS. 5-6.

In embodiments, the PV cells are furthermore sorted or binned, prior tothe assembly of each of the portions, and so as to minimize differencesbetween photovoltaic voltages of the cells, step S2. Indeed, theillumination onto the different cells of the arrays can substantiallydiffer, e.g., change from high illumination (e.g., 5 on a scale of 1 to5, as in FIG. 2) to medium illumination (e.g., 2 or 3), and lowillumination (e.g., 1). Of course, FIGS. 1-2 reflect a mere pedagogicalexample. Cells within each portion can nevertheless be sorted such thatthe relative photovoltaic voltages of the cells when illuminated duringoperation are as identical as possible, so that maximum power can beextracted. Typically, the output voltage of a cell depends onillumination and, for high-illumination regions, cells will tend toproduce lower output voltage compared with lower-illumination regions.This can be exploited by said sorting or binning of cells in order toeven out voltages during operation and allow a more efficient productionof electrical power.

Note that higher-illumination results in higher cell voltage underopen-circuit conditions (no current flow), while under operatingconditions with current flow the cells with higher illumination willhave lower voltage output due to ohmic losses on that cell, i.e., thevoltage drop due to ohmic losses outweighs the open-circuit voltageincrease at higher illumination.

Referring now to FIG. 8, another aspect of the invention is nowdescribed, which concerns a photovoltaic system 1. This system comprisesa PV module 2 such as described herein. If necessary, the system 1 maycomprise several PV modules 2. As further symbolically depicted in FIG.8, the system 1 can comprises a monitoring unit 54. The monitoring unit54 is in electrical communication with the electrical interconnects31-37 of a PV module 2 of the system 1. This monitoring unit isconfigured to monitor electrical signals provided from each of the Nportions 20, via the electrical interconnects 31-37.

In embodiments, the PV system 1 further comprises optical transmissionmeans 61, 62, positioning means 53, and a controller 54. Opticaltransmission means 61, 62 are known per se and are generally configuredto direct light onto the array 5 of PV cells 10 of the PV module 2 ofthe system 1. For example, the optical transmission means 61, 62 maycomprise an optical concentrator to concentrate light onto the array 5of PV cells 10. The optical concentrator typically comprises optics(e.g., mirrors or lenses), configured to concentrate 101-103 sunlight100 onto a small area of PV material, as known per se. Variouspositioning means 53 are known, which allow a position and/or anorientation of the optical transmission means 61, 62 and/or the PVmodule 2 to be adjusted in the PV system 1. In FIG. 8, positioning means53 are shown which allow a curved mirror 61 to be oriented with respectto sunlight 100.

The controller 54, which may be lodged in the same computerized unit 54as the monitoring unit, is operatively connected to the positioningmeans 53 to adjust positions and/or orientations, based on feedbacksignals it receives from the monitoring unit. To that aim, themonitoring unit 54 is operatively connected to the controller 54 toprovide it with feedback signals, based on electrical signals itreceived from each of the N portions 20 that it monitors, in operation.The controller 54 can be implemented by the same computerized unit 54that implements the monitoring functions. In variants, part or all ofthe functions of the monitoring unit may be implemented locally, at themodule 2, thanks to an embedded processor, operatively connected to thecontroller.

In embodiments, the monitoring unit 54 is further configured to computefeedback signals by minimizing differences between voltages outputted bythe N portions 20, based on the monitored electrical signals. Asmentioned earlier, current produced by each portion may also be used, inprinciple, as a feedback signal. Yet, relying on voltages makes it morepractical, as it allows sensing much lower light source intensities inpractice. As a result, exposure to ambient light suffices to align orcalibrate the PV module.

The above principles can be used for sun-tracking purposes in CPV orHCPV systems or to align such systems. That is, electrical signals asindependently obtained from each portions 20 of PV cells 10 may be usedto obtain feedback signals and adjust the optical transmission means 61,62, such that a symmetric illumination pattern is achieved. This, inturn, allows substantially equal currents to be generated by each of theN portions 20.

The present concepts can more generally be applied to point focussystems. Yet, the general concepts described herein may also be appliedto linear focus systems (using N=2 portions).

Next, according to another aspect, the invention can be embodied asmethods of operating a photovoltaic module 2 or a system 1 comprisingsuch a module 2, as described above. Aspects of such methods havealready been evoked in respect of FIGS. 1-8 and are therefore onlybriefly recalled now, in reference to FIG. 10. Basically, such methodsrevolve around directing light onto said array 5 of PV cells 10 (stepS10, FIG. 10), and collecting S20 an output electrical current from theN portions 20 connected in series, while electrical signals arecollected S30 from each of the N portions 20, so as to optimize theelectrical power outputted from the N portions 20.

As evoked earlier, an illumination pattern of light directed onto saidarray 5 of PV cells 10 may be adjusted S40, so as to increase electricalpower outputted from the N portions 20, based on electrical signalscollected S3 from each of the N portions. The adjustment of theillumination pattern may for example be performed by adjusting aposition and/or an orientation of the optical transmission means 61, 62and/or the array 5 of PV cells 10. This adjustment can be performedbased on voltage measurements, as obtained via electrical interconnects31-37 for each portion 20.

In particular, the illumination pattern can be adjusted by minimizingdifferences between the measured voltages. Assume for instance that thearray 5 is partitioned into four quadrants, as in FIG. 4. Here, thevoltage differences can be minimized both horizontally and vertically.That is, the difference between voltages obtained for, on the one hand,the circuit formed by quadrants 203 and 204 and, on the other hand, thecircuit formed by quadrants 201 and 202 has to be minimized, e.g., tozero, for horizontal symmetry. Meanwhile, the difference betweenvoltages obtained for, on the one hand, the circuit formed by 201 and204 and, on the other hand, the circuit formed by 202+203 has to beminimized for vertical symmetry. More generally, the voltage differencesto be considered depend on the number and arrangement of the portions,i.e., on the symmetry of the array.

As explained earlier in reference to FIG. 8, the minimization can beimplemented as a feedback circuit, involving:

Electrical interconnects 31-37, to make it possible to collectindividual electrical signals for each portions;

A monitoring unit 54, to monitor such signals and compute currentvoltage differences; and

A controller 54, which, based on feedback signals obtained from themonitoring unit, modifies a geometrical configuration of the system.

In sun-tracking applications, the illumination pattern is repeatedlyadjusted so as to track the moving light source. The same principle canbe used for aligning the array 5 of PV cells 10 and/or the opticalconcentrator towards a source of the light. In each case, the aim is tooptimize the electrical power outputted from the portions 20 of PVcells.

Computerized devices, such as the device 54, can be suitably designedfor implementing parts of the functions described herein. In thatrespect, it can be appreciated that the methods described herein arelargely non-interactive and automated. The methods described herein canfor instance be implemented in software (e.g., firmware), hardware, or acombination thereof. In exemplary embodiments, the methods describedherein are implemented in software, as an executable program, the latterexecuted by suitable digital processing devices. More generally,embodiments of the present invention can be implemented wheregeneral-purpose digital computers, such as personal computers,workstations, etc., are used.

For instance, the computerized device 54 shown in FIG. 8 may be, e.g., ageneral-purpose computer. In exemplary embodiments, in terms of hardwarearchitecture, the unit 54 includes a processor, a memory coupled to amemory controller, and one or more input and/or output (I/O) devices (orperipherals) that are communicatively coupled via a local input/outputcontroller, which may further ensure data communication to and from theinterconnects 31-37. The input/output controller may have additionalelements, such as controllers, buffers (caches), drivers, repeaters, andreceivers, to enable communications. Further, the local interface mayinclude address, control, and/or data connections to enable appropriatecommunications among the aforementioned components.

While the present invention has been described with reference to alimited number of embodiments, variants and the accompanying drawings,it will be understood by those skilled in the art that various changesmay be made and equivalents may be substituted without departing fromthe scope of the present invention. In particular, a feature(device-like or method-like) recited in a given embodiment, variant orshown in a drawing may be combined with or replace another feature inanother embodiment, variant or drawing, without departing from the scopeof the present invention. Various combinations of the features describedin respect of any of the above embodiments or variants may accordinglybe contemplated, that remain within the scope of the appended claims. Inaddition, many minor modifications may be made to adapt a particularsituation or material to the teachings of the present invention withoutdeparting from its scope. Therefore, it is intended that the presentinvention not be limited to the particular embodiments disclosed, butthat the present invention will include all embodiments falling withinthe scope of the appended claims. In addition, many other variants thanexplicitly touched above can be contemplated.

What is claimed is:
 1. A method of operating a photovoltaic module, themethod comprising: directing light onto an array of photovoltaic cells,or PV cells, wherein the array consisting of N portions, N>=2;collecting an output electrical current from N portions connected inseries via electrical interconnects, N being even, the electricalinterconnects consisting of N−1 number of peripheral conductors, Nnumber of top electrode elements, and N number of bottom electrodeelements positioned below the top electrode elements; and collectingelectrical signals from each of the N portions, wherein: all of the PVcells in the array are arranged to be circumscribed within a boundary;the peripheral conductors are positioned along predefined edges of theboundary so as to circumscribe all of the PV cells therein and such thatthere is no overlap between the PV cells being circumscribed within theboundary and the peripheral conductors along predefined edges of theboundary; each of the top electrode elements has an end part and anopposite end part, the end part being positioned within the predefinededges of the boundary and the opposite end part extending over theperipheral conductors along the predefined edges of the boundary foronly N−1 number of the top electrode elements; each of the peripheralconductors crosses two adjacent portions of the N portions, each of theperipheral conductors comprising a piece that extends under the oppositeend part of only one of the top electrode elements, the peripheralconductors on different edges of the predefined edges being physicallyseparated from one another such that one peripheral conductor on oneside of one of the PV cells is physically separated from anotherperipheral conductor on an adjoining side of the one of the PV cells. 2.The method according to claim 1, further comprising adjusting anillumination pattern of light directed onto said array of PV cells toincrease electrical power outputted from the N portions, based onelectrical signals collected from each of the N portions.
 3. The methodaccording to claim 2, where: adjusting the illumination pattern isperformed by adjusting a position and/or an orientation of an opticalconcentrator and/or the array of PV cells.
 4. The method according toclaim 2, where: the method further comprises, while collectingelectrical signals from each of the N portions, measuring, via saidelectrical interconnects, a voltage from said each of the N portions;and adjusting the illumination pattern is performed based on voltagesmeasured for the N portions.
 5. The method according to claim 4, where:adjusting the illumination pattern is performed so as to minimize one ormore differences between measured voltages.
 6. The method according toclaim 3, where: directing light onto said array of photovoltaic cellscomprises concentrating light onto said array of PV cells.
 7. The methodaccording to claim 3, where: said illumination pattern is repeatedlyadjusted so as to track a moving source of the light.
 8. The methodaccording to claim 3, for aligning a photovoltaic system, or PV system,where: the method further comprising, while collecting electricalsignals from each of the N portions: aligning the array of PV cellsand/or the optical concentrator towards a source of the light, toincrease electrical power outputted from the N portions.
 9. A method offabrication of a photovoltaic module according to claim 1, the methodcomprising fabricating said array of PV cells and said electricalinterconnects.
 10. The method according to claim 9, where: fabricatingthe array of PV cells comprises, for each of the portions, sorting cellswithin said each of the portions to minimize differences betweenphotovoltaic voltages of the sorted cells.
 11. The method of claim 1,wherein the top electrode elements are formed in a rotationalarrangement in a geometric shape to circumscribe all of the PV cellswithin the boundary and the peripheral conductors along predefined edgesof the boundary, the rotational arrangement having the opposite endparts each extend out in different directions toward the predefinededges of the boundary.
 12. The method of claim 1, wherein the topelectrode elements comprise elongated contact elements perpendicular toa base.
 13. The method of claim 1, wherein the N portions each comprisean equal number of the PV cells such that the equal number of the PVcells are electrically connected by the peripheral conductors along thepredefined edges.